Method of treating brake drums or the like



April 16,1935. w. H. FARR 1,998,048

v ING BRAKE DRUMS OR iHE LIKE Filed 'July 12, 1930 IN VEN TOR. WneeE/v Ii five:

FIG-4 KM ATTORNEY.

METHODOF TItEATING RAKE DRUMS g y oarnnuxn.

Warren H. Farr, Detroit, Mich.,assignor to Budd Wheel Company, Philadelphia, Pa.,-a corporat 7 tion of Pennsylvania Application iulyl2,

1930, Serial 467,53 7

10 c aims. (01. 29-1523).

; My invention relates to a method of treatment adapted to be applied'to the internal peripheral surface of a brake drum or other annularwork piece. v V a It, is a main object of my inventionto subject such work pieces. to a method of treatmentwhich will improve their weargresistingqualities and reduce. them to accurate size and true surfaces of revolution. s 1

Brake drums have heretoforebeen produced by various pressing and rolling operations and, frequently, expensive heat :treating and: machining operations to reduce them to the accuracy of. size and true surfaces of revolutionand the hardness desirable for long life andsmooth operation of the. drums and the brake shoes cooperating there- By my invention .1 am ableto avoid a number of the operations heretofore required and to at: tainthe. objects of theinvention by the. simple expedient of .swaging the internal periphery. of the drum while supportingit on itsexternal periphery. By this method. I amalso enabled to salvage brake drums having their peripheral surfaces distorted or undersize without expensive rolling or' machining operations,.and hence'at 'very low cost. The methodof my invention not only hardenstheinner peripheral braking surface so as to greatly increase its life, but the swaging operation produces a similar sefiectain the outer peripheral surface,-increasing the wear-resisting qualities of that surface, making thev same brake drum very suitable for use either forlexternal or internal-brakingor both. I

'In the practice of the method of myinvention,

the bestresults areobtain'edifbut a relatively small arc of the surface is treated at an-instant of time, and it is desirable to treat the surfaces at oppositeends of a diameter simultaneously by radially acting hammers to enable the forces to."

be equally balanced. To speed up the work and to treat all" parts of the surface equally, the swaging means and the work are relatively rotatedat an appropriate speed and the hammers are.op-' erated to strike the blows at great rapidity, where- .by the entire surface of the work may be treated inaminimum of: time.

Another feature of the methodconsistsin the gradual feeding of the hammers outwardly into the work until the desired sizeis reached, and the continuation of the swaging after the feeding a .sufi'icientlength of time to reduce theentire surface to a true surfaceof revolution, due, to the overlapping ofthe successiveblows in the relative rotation of the work and swaging means.

' Figs. 1 and ,2 show,,re

mers and being worked. whether hard or soft. For. low

method of this invention. u i

Inthisdrawing, I} 5 i v 'pectively, an inside elevation .and an axial sectional .view ofa work piece, in this-case, abrake drum adapted to be treated by my improved method.

Figs. 3 and 4 show. more'or less diagrammatl0- ically transverse sectional views. of a. form of apparatus which may be used to'carry out the method, in two. different positions of the hamj the actuating mechanism therefor. igs. 5 and 6 are detail axial sectional views of the work piece and the adjacent parts of-the' apparatus, respectively, at the'beginning and the end of the swaging operation} r i In the practice ofmy invention, I take a brake drumorother work piece as IE3, having an inner peripheral surface, as l I, and an outer peripheral surface l2'adapted :to be treated, as it comes from the forming press or otherwise roughly of the desired shape andsize, and clamp it (mas outer peripheral surface in a series of'clamping jaws, l3 of a form on their inner faces Moonforming to the outer peripheral surface which it is desired to, produce. These jaws, in the case illustrated, form dies, together. forming an inner cylindrical surface entirely surrounding the outer face of the drum, i'. e., they form a. support or anvil against whichvthelinternal swaging means may act upon the work.

In a suitable annular support l5 arranged inside theinner peripheral face ll of the drum. which support is, in the practiceof the invention, held in true axial alignment with the axis of the work clamping jaws are arranged a series of hammers Ioadapted to have limited radial movement in the support. These hammers havea working face extending axially, and of a width axially to operate in the width of surface to be treated. Preferably, in order to work but a small arc ofthe surface of the work at each blow of the hammers, the working face ll is formed, as shown,- on an arc of relatively; small radius but,

. of course, the curvature of the working facewill dependsomewhat uponthe-nature of the. metal carbon steel, such as-is commonly used. forjdie drawing a brake drum, I have obtained good results with a working face substantially of a radius relative to the surface to be welded such as. that indicated in the drawing.

Thehammers. fi..a e.r reir a ran ed. in

balanced arrangement about the axis of the support i and clamping jaws l6 and at opposite ends of a diameter, and, in the practice of the method, two diametrically arranged hammers are actuated simultaneously to work on opposite points of the work.

The hammers can be simultaneously actuated by any suitable means. In the illustrated embodiment of an apparatus adapted to practicethe method I have shown an actuating means there- I for which comprises a shaft {8 adapted to have a high speed of rotation relativeto the support" only of hardening the inner peripheral face 12 of thework, but also of hardening the outer surface 1] as well, thus simultaneously producing in one in which the hammers are mounted, and this-shaft is provided with equally spaced; radial slots 4 43 within which are located also for liinitedradial movement, the rollers 20. These rollers are preferably of frusto-conical form, and they are swept around with the rotation of the shaft; to enable each in succession to strike an axiallyextending actuating rib 2! formed on the inner face of each hammer and adapted, when the hammers are in their inner positions 'radia'lly, to project'into the path of the rollers. These rollers shown in Figs. 3 and 4 in their outer positions wherethey actuate the hammers to deliver the finishing blows to the surface of the work, are supported on their inner sides by what maybe-called-anactuator head -22, which-is also preferably "of frusto-conical form to match the incline of the surface of the rollers.

At the beginning of the'sw'aging operation, this actuator head, which is adjustable axially 'to-fe'e'd the rollers outwardly'and thus feedthe hammers into the work, to expand it against the faces 14 of outer supporting jaws H, are permitted ;to move inwardly when they come'opposite the actuating ribs 2| on the 'harnmers'because the actuator headis so'axially adjusted as to permit this. When the swaging operation commences, the work supporting jaws l4 and-the work held therein are rotated relative to the hammer support [5 at a relatively slow speed and the actuator head is gradually fedaxially in a directionto cause the rollers to meet their support unit-on a largerand larger diameter, and this movement, the hammers are at each'passage of a' rollerpast their actuating ribs forced deeper and deeper into-the work, until they reach their outer position shown in Figs. 3 and 4, where the hammers are-exert ing their finishing blows upon the work. The

rollers aresoarranged, see Figs. ;3 and 4, that the diametrically opposed hammers-aresimultaneously operated-to strike their blows, but these blows are only momentary ones-since thearcuate faces I8 of the actuator ribs are formed on arelatively small radius. Byreasonof the roller contact with these 'arcuate faces, and the high rate of speed of the actuator shaft 18, the blows-are struck with great rapidity, and yet without absorbing a great deal of energy; The rotationof the work insures-each partof its peripheral surface being struck many blowsduring the treatment Thus the method of my inventionis rapidly carried out. 'The metal of the brake drum" is worked between the surfaces 14 of the clamping jaws, which act as an anvil, and the hammers Swhich act to expand and true the inner peripheral "surface I 2 of the drum, and to give it the exact dimension desired, and the outer peripheral'surface ll of the drum isat the same time, through its engagement with the inner true surface of the clamping jaws alsogiven the exact size desired. The swaging so carried'out'by'strib ing a great number of hammer b'lows against all partsof the periphery of the'dr'um, especially if "axis of a drum.

' prolonged.

' The s'w'agin'gby this method, has the effect not operation a brake drum having an outer and innersurfacehardened to provide a wear resisting braking surface.

Eromthe foregoing description it will be seen that not only have I produced a novel method of treatment which adapts existing types of brake made of low carb'o'n steel or other metals adapted for die drawing, but'not having longwear resisting qualities, to be readily converted into brake drums having --such qualities because my method imparts these qualities to them, "but I am also able to salvage, by the practice-of my method, brake drums which have become distorted after the drawing operationyso asto be unfit for use, except through expensive re-heating and rolling or machining operations, and to make out "of them an'accurately sized, true and long-life productsa a v H What I'clai'm is: J a

1.. The method of treating brake drums which consists in "supporting them peripherally and swaging them internally by application ofsuc cessive blows, each of which extends on a line parallel to the axis of a drum. 1 it 2. The-method of treating brakedr-ums which consists in supporting themyperipherally .and swaging them "internally by application of:-successive blowsyeaoh of which extends onaline parallel to means of a drum and rotating them while swaging.

3. The methodof treating brakedrumswhich consists in supporting them over. substantially the=entirecircumference of their outer peripheral surfaces and swaging' them internally ;over 7 the circumference of. their internal peripheral surface to increase: the wear resisting qualities of both said outer and inner surfaces simultaneously byapplication of successive blows, each of which extends on a. linefparallel to the axis'of ajdrum. "5'4. The methodof treating a brake drum which comprises swaging the braking surface thereof by applicationof successive blows, eachsof which extends on a line parallel to the axis-of a 'drum.

5. :Themethod of treatinga brake drum which comprises swaging an'interior surface thereof to produce-a suitable braking surface by, application of successive blows, each of 'whichextends one, line parallel to the axis of a drum. a i

6. The method of forming a-brake drum which comprises selectively compacting'the braking surface thereof by applicationpf successive blows, each of which extends onialin'e parallel to the 7. The method oftrea'ting annular workpieces which consists in supporting them peripherally and swagin'g theminternally by operating simultaneously 'up'on diametrically opposite sides there- "of, by application of successive blows; each of which extends'on aline parallel to the axis of a 8. The method of treating brake drums which consists in supporting them peripherally and swaging them internally by operating simultaneously upon diametrically opposite sides thereof while rotating them, by application of successive blows, each of which extends on a line parallel to the axis of a drum.

.9. The method of'working an annular object, which comprises radially backing the object entirely about its perimeter at one side, and beating it against the backing from the opposite side by applying an annular series of radially oppositelyjdirected simultaneous blows successively over small areas and of suflicient force to locally distort the object over such small areas.

10. The method of working an annular object, which comprises setting up a rotary motion about the axis of the object and converting such motion into a rapidly applied annular series of rectilinear oppositely directed simultaneous radial thrust blows toward, and covering only small areas of,

such small'areas. V

v WARREN FARR;

the objectandsuflicient to distort the object on 10 Y 

